1. Field of the Invention
The present invention relates to a spine fixator for aligning and holding a backbone.
2. History of the Related Art
Fixators of this type are known, which generally comprise two parallel assemblies, each comprising:
a cylindrical rod whose length is determined as a function of the number of stages to be joined; PA1 and a plurality of assemblies composed of a ring, a nut and a pedicular screw or of hooks allowing the rods to be fixed on the vertebrae. PA1 a slideway in the form of a U having a bottom is pierced with an open slot therein; PA1 a plurality of rings which have a horizontal opening if an inner profile corresponding to that of the slideway, a tapped bore coaxial with a smooth hole in the bottom of the ring perpendicularly to the opening; PA1 pedicular screws with self-tapping thread and spherical head, allowing the slideway to be put in place and positioned in the ring; PA1 and a threaded cap screwed in the tapped bore of each ring and which each abut on the upper part of the head of the screw so as to assemble by tightening the ring and the slideway via the head of the screw.
Other fixators comprise plates perforated with holes or slots allowing passage of screws being implanted in the pedicles.
Such fixators present certain drawbacks concerning the risks of micro-movements or of fragility of the connection either between the screw and the rod or between the screws and the plates.
Moreover, the fixators employing plates impose a pedicular spacing which may not be adapted to anatomic variations.
It is a particular object of the present invention to overcome these drawbacks.